Unconsolidated Affiliates and Noncontrolling Interests (Variable Interest Entities) (Details)	Jun. 30, 2017 USD ($)
Ambassador Infrastructure, LLC
Noncontrolling Interest [Line Items]
Investment in Real Estate Joint Ventures and Partnerships	$ 0
Maximum Risk of Loss	$ 11,035
Percentage of debt guaranteed	100.00%
G&I VIII CBL Triangle LLC
Noncontrolling Interest [Line Items]
Investment in Real Estate Joint Ventures and Partnerships	$ 2,103
Maximum Risk of Loss	$ 2,103